Loaded cable circuit



June 10, 1930. I ALEBELINGI v 1.75236 LOADED CABLE cmcurr Filed May 18. 1929 Ill flf/Ffi dF/RALEDQUAD v I v I i DOUBLE 01/40 INVEN7DR A. EBESLING Arm/way Patented June 10', 1930 UNI-TED. STATES- PATENT orilcs AUGUST EIBELING-i or cnARLo'rrENBUne, GERMANY, ASSIGNORS TO SIEMENS & 'HALSKE AKTIENGESELLSCHAFT, or srnmnnss'ran'r, NEAR BERLIN, GERMANY, A

COMPANY OF GERMANY LOADED CABLE cmcurr Application filed May 18, 1929, Serial No. 364,145, and in- Germany May 26, 1928.

This invention relates to electrical transmission and particularly to the transmission of signaling currents through cable circuits. In a United States application of Karl Kupfmuller, Serial No. 234,452, filedNovember 19, 1927, upon which Patent No. 1,719,478 was granted July 2, 1929, there is disclosed a loaded telephone cable system made up oftwo different kinds of quads. One kind comprises multiple twin quads and the other comprises the so-called spiral quad. In the former-the two wires forming one telephone circuit are twisted together and this pair is twisted with another pair similarly formed. In the spiral quad formation the four wires forming twotelephone lines are all twisted together. As pointed out in the Kupfmuller patent, a cable may advantageously be composed of both of these types of quads in ,order to provide circuits which when suitably loaded may be most advantageously used both in side circuit and phantom'circuit connections for traversing different distances.

' The present inventiongoes a step farther and provides further advantages by combining with the two types of quadsabove mentioned, a third type of quad known as a double quad, formed by twisting together eight wires forming four two-wire telephone circuits as so will beldescribed more fully hereinafter. v e As will; presently be shown the double quad may'have difl'erent attenuation and/or cut-off frequencies from either of the other two types mentioned and may therefore advantageously be used in connection with those types of quads to provide a greater variety of circuits suited to different transmission conditions. f The invention will, be more clearly underv stood from the following detailed description.

this invention.

In the drawing the three figures represent f respectively, the three types of quads to flb'e combined into a cable in accordance with- Referring to the drawing, Fig. 1 shows a vmultip e twin quad formation in which the twisted together to'form a {second twisted strand. These two strands are then twisted around each other to form a quad.

Fig. 2 shows the formation of a spiral quad.

Line wires 1, 2, 3 and 4 are twisted together to form a single four-Wire strand. A

Fig. 3 shows the formation of a double quad. This comprises eight line wires forming four two-wire circuits A, B, C and D.

These two-wire lines are wound around a common axis in the same way as the single wires" the side circuits. The smaller phantom shunt capacity in the double quad formation is probably accounted for by the fact that the distance between the side circuit conductors which go to make up the phantom is greater than in the case of the other types of quads. As in the Kupfmuller patent referred to, a cable will preferablybe made up to contain different typesof quads which will be loaded to suit the transmission conditions so as to obtain the best over-all transmission fordifferent lengths of line.

In the case of a coil loaded line where the line resistance per unit length is R, the capacity per unit length is C, the coil spacin is s and the cut-off frequenoy'F the speci c attenuation b is given by th elation d the side circuit by thesubscript ce he phantom circu t}res'stance is lf the side circuit resista' we get assuming the same spacing of thel'oading coils in both cases.

If the phantom and side circuits are conphantom circuit {by the substructed to-have the same attenuation, it is seen from the above relationship that the cut-off frequency of the phantom is twice that of the side circuit. When the circuits are thus constructed to have the same attenuationthey are suitable for the same typeof circuit connection (eithertwo-wire or fourwire transmission) but are advantageously used for diflerent length circuitspn account of the difference in cut-off frequencies. Thus the phantom circuit may advantageously be used for transmission to a greater distance than the side circuits.

As was disclosed in the Kupfmuller patent the multiple twin quad gives a capacity ratio of phantom circuit to side circuit of 1.65 and the spiral quad gives a ratio of phantom circuit capacity to side circuit capacity of 2.75. The fact of these two ratios and the accompanying difference in cut-off frequencies in the side circuits and phantom circuits using these two types of quads provides in the same cable different types of circuits suited to different distances of transmission as more fully set forth in the Kupfmuller' patent;

In the ease of the double quad, the capacity ratio between phantom and side circuit is about unity so that when this type of quad is added to the other types inentioned,that is, when all three types are combined into a cable structure, the cable is better adapted to meet various transmission requirements than when only two types are used. The principles laid down in the Kupfmuller patent for the selection of the-type of quad and the type of loadmg to be used are applicable also to the presentdinvention where the double quad is also use An incidental advantage v of using the double quad formation in connection with the multlple twin quad and the spiralquad in making up a cable is economy of space. Each 7 type of quad has a different cross-section. It

is common in constructing a cable of uniform types of quads to increase the number of quads in-each layer by six, proceeding from the coreof the cable outward. The'use of d fferent types of quads offers the opportun ty to vary the number to suit the difierent dlameters and may result in some casesin an economy of space. Q

Instead of constructing the phantom and side circuits of a double quad to have the i same attenuation they may be made to have the same cut-off frequencies. When this is done the specific attenuationof the side circuit becomes about twice that of the phantom circuit. These values fit the practical case of four-wire and two-wire repeater circults. For example, with a repeater spacing of 140 km., a line attenuation of 2.8 Napier is at present used for a four-wire circuit and a line attenuation'of 1.4 Napier for a two wire circuit. This means thatthe four-wire circuit may employ wires and the two-wire circuit 1.4; mm. diameter line wires. Where double quads are used in accordance with this invention various attenuationsfor four-wire and two- Wire connections may be obtained by using the same gauged wire.

\Vhat is claimed is:

1, In a telephone cable, spiraled quads forming phantomand side circuits, multiple twin quads forming phantom and side circuits, and double quads forming phantom and side circuits, said side circuits and phantom circuits being loaded.

2. In a telephone cable, three types of quads, namely, double quads, multiple twin and spiraled quads, each type forming side and phantom circuits, said side and phantom circuits being loaded, the ratios of phantom to side circuit capacities in the three types .9 mm. diameter line" being respectively approximately unity, 1.6 v

01' 1.7, and 2.7 or 2.8.

3. A telephone cable according to claim 1 in which certain of the double quads are designed to have equal specific attenuation in i the side and phantom circuits.

4. A telephone cable according to claim 1 in which certain of the double quads ate designed to have substantially the same :cut-oif frequency for the side and phantom circuits.

In witness whereof, I hereunto subscribe my name this 1st day of May, 1929.

I AUGUST EBELING. 

